PSI - Issue 64

H.F. Stewart et al. / Procedia Structural Integrity 64 (2024) 573–579 Stewart, Cusson, Greene Gondi & Oliver / Structural Integrity Procedia 00 (2024) 000–000

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A series of apparently periodic undulations are visible in the elevation profile obtained from the tri-stereo DSM. These undulations are approximately 130 m from peak-to-peak on the west side of the bridge, with a peak-to-trough distance on the order of 0.8 m, and approximately 80 m from peak-to-peak east of the Seaway navigation channel with a peak-to-trough distance on the order of 1 m. The cause of these undulations is not known. We note that a peak-to trough distance of 1 m is within the 1.5 m LE90. Fig. 5 shows a comparison of the georeferenced PS targets near Pier W17, Pier E02, and Pier E07 using the SRTM DEM only (top row), SRTM with Manual Editing (ME, centre row), and the merged SRTM and Pleiades DSM (bottom row). Several improvements are observed. Horizontal geolocation offsets of up to 42 m along the top of the bridge deck that are visible in the SRTM DEM-only geocoded targets are corrected by both manual editing and with the merged DSM, as seen by the alignment of PS targets on overhead road sign gantries in all three locations. Additionally, the broadly spaced groups of PS targets associated with the overhead sign gantries have a much denser clustering than was obtained from the original georeferencing or after the manual adjustment. Finally, the angular relationship between PS targets and real bridge elements is improved. In future work, the DSM merging process could be semi-automated and performed without significant manual effort. 4. Summary and conclusions This paper is a preliminary assessment of whether DSMs obtained from tri-stereo satellite imagery are suitable for supporting PS-InSAR analysis in RS-SHM workflows. The Pleiades tri-stereo DSM adequately captured the asymmetrical elevation profile of the subject bridge, and the vertical accuracy of this DSM was within expected tolerances. Merging the Pleiades tri-stereo DSM with the SRTM DEM and using this merged DSM for height analysis provided significantly improved accuracy relative to heights estimated from the DEM only and moderate improvement relative to the manual height correction method. Further investigation into using satellite-based DSMs as part of a larger RS-SHM process is planned. Acknowledgements This research was jointly funded by Transport Canada and Infrastructure Canada through NRC’s Climate Resilient Built Environment (CRBE) Initiative. References Airbus Defence and Space, 2021. Pléiades Neo User Guide. V3.0, Toulouse, France, 64 p. American Society for Photogrammetry and Remote Sensing, 2023. ASPRS Positional Accuracy Standards for Digital Geospatial Data. 2 nd Ed. V 1.0, Baton Rouge, USA, 92 p. Astrium, 2012. Pléiades Imagery User Guide. V2.0, Toulouse, France, 118 p. Cusson D, Stewart H., 2024. Satellite Synthetic Aperture Radar, Multispectral, and Infrared Imagery for Assessing Bridge Deformation and Structural Health—A Case Study at the Samuel de Champlain Bridge. Remote Sensing. 16(4):614. https://doi.org/10.3390/rs16040614. Données Québec, 2022. Ville de Montreal LiDAR Aérien 2015. Montreal, Canada. Accessed 11 March 2024 at https://www.donneesquebec.ca/recherche/dataset/vmtl-lidar-aerien-2015. FCM, 2019. Canadian Infrastructure Report Card 2019 - Monitoring the State of Canada’s Core Public Infrastructure. The Canadian Federation of Municipalities, Ottawa, Ontario, Canada, 56 p. (http://canadianinfrastructure.ca/downloads/canadian-infrastructure-report-card-2019.pdf). Hobi ML, Ginzler C., 2012. Accuracy Assessment of Digital Surface Models Based on WorldView-2 and ADS80 Stereo Remote Sensing Data. Sensors. 12(5):6347-6368. https://doi.org/10.3390/s120506347. Loghin AM, Otepka-Schremmer J, Pfeifer N., 2020. Potential of Pleiades and WorldView-3 tri-stereo DSMs to Represent Heights of Small Isolated Objects, Sensors. May 9;20(9):2695. doi: 10.3390/s20092695. MDA Geospatial Services, 2021. InSAR Analysis of Satellite Imagery Over Bridge Sites: Champlain Bridge, Montreal (QC), Technical Report No 617-21-260-02 for NRC. 30 September, 40 p. Ministère de l’Énergie et Ressources Naturelles Québec, 2024. Fiche signalétique “94K4330.” Quebec City, Canada, Accessed 21 March 2024 at https://fichegeodesique.mern.gouv.qc.ca/matricule-datum/94K4330/2. Panagiotakis E, Chrysoulakis N, Charalampopoulou V, Poursanidis D., 2018. Validation of Pleiades tri-stereo DSM in Urban Areas. ISPRS International Journal of Geo-Information. 7(3):118. https://doi.org/10.3390/ijgi7030118. St. Lawrence Seaway Management Corporation, 2019. Seaway Handbook: Montreal – Lake Ontario Region Guide. Cornwall, Ontario, Canada.